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Talk19 min

Optimising recall from tape using Archive Metadata

Julien Leduc · CERN

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During Run-3, CTA has demonstrated very high write efficiency at nominal DAQ rates. For retrieval, CTA relies on time-based colocation of data on tape, but this has proved to be much less efficient than expected. Furthermore, the ratio of tape reads to writes is expected to significantly increase during Run-4, as some LHC experiments move towards the "tape carousel" model. Two years ago, we started to analyse the constraints from the experiments and tape sites, in order to devise a way to improve retrieve efficiency. The resulting Archive Metadata proposal is a practical abstraction layer between experiment data management and tape storage endpoints. It allows to express how group of files are likely be staged together. This talk will present how this project has evolved over the past two years, its initial proposal implementation and finally an overview of the collected metadata during the 2024 Heavy Ion run. Finally, we will also give an overview of the plan for upcoming research and development using Archive Metadata..

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The talk

  1. Optimising recall from tape using Archive Metadata 2025-03-28 · 19 min · CERN's player

Credits and licence

Institution
CERN
Department
HEP Computing
Speaker
Julien Leduc
Year
2025
Language
English
Subjects
Computer science
Source
CERN
Licence
CERN, as CERN states it. CERN's terms
Attribution
© CERN. CERN provides its audiovisual media free of charge for educational and informational use, credited to CERN; this lecture is shown in CERN's own player.
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